How do you calculate the estimated due date (EDD)?

The method for calculating the estimated due date (EDD) is based on the assumption that a full-term pregnancy lasts about 40 weeks, or approximately 280 days, from the first day of a woman's last menstrual period (LMP). This standard method typically involves taking the first day of the LMP, subtracting 3 months from that date, and then adding 7 days.

By subtracting 3 months, you align the date with the typical gestational age of the fetus at conception. The addition of 7 days helps to adjust the initial date to better reflect the expected delivery date, resulting in what is commonly known as Naegele's Rule.

Using this approach can help healthcare providers estimate a woman's due date more accurately, allowing for appropriate prenatal care and preparation for delivery. This method is widely recognized and utilized in obstetrics.